GVV858 alone or with fulvestrant or letrozole for HR+/HER2- breast cancer and other advanced tumors

An Open-label, Multi-center, Phase I/II Study of GVV858 as a Single Agent and in Combination With Endocrine Therapy in Patients With Advanced Hormone Receptor Positive, HER2- Negative Breast Cancer and Other Advanced Solid Tumors

Phase1; Phase2 Interventional Novartis · NCT07288359

This trial tests whether GVV858 alone or with fulvestrant or letrozole can help adults with HR+/HER2- advanced breast cancer, CCNE1‑amplified solid tumors, or metastatic castration‑resistant prostate cancer.

Quick facts

PhasePhase1; Phase2
Study typeInterventional
Enrollment205 (estimated)
Ages18 Years and up
SexAll
SponsorNovartis Industry-sponsored
Drugs / interventionschemotherapy
Locations5 sites (Nashville, Tennessee and 4 other locations)
Trial IDNCT07288359 on ClinicalTrials.gov

What this trial studies

This first-in-human, open-label Phase I/II trial gives GVV858 as a single agent and in combination with fulvestrant or letrozole across several advanced cancer cohorts. Phase I uses dose-escalation with possible expansion cohorts to define safety, tolerability, and a recommended dose for further study. A combination arm may proceed into a randomized, open-label Phase II with optional dose optimization specifically in HR+/HER2- advanced breast cancer. Efficacy signals will be explored alongside safety, with expansion cohorts stratified by disease type and CCNE1 amplification where applicable.

Who should consider this trial

Good fit: Ideal candidates are adults with HR+/HER2- advanced breast cancer who progressed after endocrine therapy plus a CDK4/6 inhibitor and additional systemic therapy, patients with advanced solid tumors harboring CCNE1 amplification, or men with metastatic castration‑resistant prostate cancer meeting the trial's prior-therapy limits.

Not a fit: Patients with early-stage disease, tumors without CCNE1 amplification for the targeted cohorts, those with a neuroendocrine component in prostate cancer, or those who do not meet the prior-therapy requirements are unlikely to benefit from this early-phase trial.

Why it matters

Potential benefit: If successful, GVV858 could provide a new targeted treatment option that slows tumor growth for patients with HR+/HER2- breast cancer or CCNE1‑amplified tumors and potentially extend progression-free survival.

How similar studies have performed: Combining targeted agents with endocrine therapy has improved outcomes in HR+/HER2- breast cancer (for example CDK4/6 inhibitors), but GVV858 is first-in-human and its specific approach has not yet been proven in patients.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Age ≥ 18 years old.
* Patients with one of the following histologically or cytologically confirmed advanced cancers:

Phase I (patients with one of the following cancers, from whom no standard therapy is available or appropriate in the judgment of the investigator):

* HR+/HER2- advanced breast cancer (aBC) with disease progression on or following at least one line of hormone-based therapy in combination with a CDK4/6i and at least one additional line of systemic therapy for metastatic disease.
* Locally advanced or metastatic cancer with a CCNE1 amplification. For dose expansion only: no more than 3 prior lines of therapy for advanced or metastatic disease.
* Metastatic castration-resistant prostate adenocarcinoma, with no documented neuroendocrine component, castrate level of testosterone, and no more than 3 prior lines of systemic therapy for metastatic disease.

Phase II:

* HR+/HER2- aBC with disease progression on or after an endocrine therapy in combination, with a CDK4/6 inhibitor for advanced disease with no more than 2 lines of endocrine therapy and no prior cytotoxic chemotherapy or antibody-drug-conjugate for advanced disease.

  \- Measurable disease as determined by RECIST v1.1.
* BC only: If no measurable disease is present, then at least one predominantly lytic bone lesion must be present that can be accurately assessed at baseline and is suitable for repeated assessment.
* metastatic Castration-Resistant Prostate Cancer (mCRPC) only: If no measurable disease is present per PCWG3 modified RECIST, then at least 1 metastatic lesion must be present on bone scan imaging.

Exclusion Criteria:

* Patients with inadequate bone marrow and/or organ functions with out-of-range laboratory values.
* Clinically significant, uncontrolled heart disease and/or cardiac repolarization abnormality including myocardial infarction (MI), coronary artery bypass graft (CABG), long QT syndrome, or risk factors for Torsades de Pointes (TdP).
* Presence of symptomatic central nervous system (CNS) metastases or CNS metastases that require local therapy or increasing doses of corticosteroids within 2 weeks prior to study entry.
* Patients with symptomatic visceral disease, including visceral crisis.
* For patients with BC: Patient is concurrently using hormone replacement therapy.
* Women of childbearing potential who are unwilling to use highly effective contraception methods, pregnant or nursing women.

Other protocol-defined inclusion/exclusion criteria may apply.

Where this trial is running

Nashville, Tennessee and 4 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Advanced HR+/HER2- Breast CancerAdvanced CCNE1-amplified Solid TumorsMetastatic Castration-resistant Prostate CancerGVV858FulvestrantLetrozoleBreast CancerCCNE1 amplification
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.